Methods for forming semiconductor materials by atomic layer deposition using halide precursors

ABSTRACT

Methods of depositing a III-V semiconductor material on a substrate include sequentially introducing a gaseous precursor of a group III element and a gaseous precursor of a group V element to the substrate by altering spatial positioning of the substrate with respect to a plurality of gas columns. For example, the substrate may be moved relative to a plurality of substantially aligned gas columns, each disposing a different precursor. Thermalizing gas injectors for generating the precursors may include an inlet, a thermalizing conduit, a liquid container configured to hold a liquid reagent therein, and an outlet. Deposition systems for forming one or more III-V semiconductor materials on a surface of the substrate may include one or more such thermalizing gas injectors configured to direct the precursor to the substrate via the plurality of gas columns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/357,805, filed Jan. 25, 2012, which application is a divisional ofU.S. patent application Ser. No. 12/895,311, filed Sep. 30, 2010, nowU.S. Pat. No. 8,133,806, issued Mar. 13, 2012, the disclosure of each ofwhich is incorporated herein in its entirety by this reference. Thesubject matter of this application is related to the subject matter ofU.S. Patent Provisional Application Ser. No. 61/157,112, which was filedon Mar. 3, 2009 in the name of Arena et al., and to the subject matterof U.S. patent application Ser. No. 12/894,724, filed Sep. 30, 2010, inthe name of Ronald T. Bertram, Jr. and entitled “Thermalizing GasInjectors for Generating Increased Precursor Gas, Material DepositionSystems Including Such Injectors, and Related Methods,” the entiredisclosure of each of which is incorporated herein in its entirety bythis reference.

FIELD

Embodiments of the invention generally relate to systems for depositingmaterials on substrates, and to methods of making and using suchsystems. More particularly, embodiments of the invention relate toatomic layer deposition (ALD) methods for depositing III-V semiconductormaterials on substrates and to methods of making and using such systems.

BACKGROUND

III-V semiconductor materials are rapidly developing for use inelectronic and optoelectronic applications. Many III-V semiconductormaterials have direct band gaps, which make them particularly useful forfabricating optoelectronic devices, such as light-emitting diodes (LEDs)and laser diodes (LDs). Specific III-V semiconductor materials, such asgallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN) andtheir alloys (commonly referred to as the III-nitrides), are emerging asimportant materials for the production of shorter wavelength LEDs andLDs, including blue and ultra-violet light-emitting optoelectronicdevices. Wide band gap III-nitrides may also be utilized forhigh-frequency and high-power electronic devices due to theIII-nitrides' ability to operate at high current levels, high breakdownvoltages and high temperatures.

One widely used process for depositing III-V semiconductor materials isreferred to in the art as metal-organic chemical vapor deposition(MOCVD). In MOCVD processes, a substrate is exposed to one or moregaseous precursors in a reaction chamber, which react, decompose, orboth react and decompose in a manner that results in the epitaxialdeposition of the group III-V material on a surface of the substrate.MOCVD processes are often used to deposit III-V semiconductor materialsby introducing both a precursor containing a group III element (i.e., agroup III element precursor) and a precursor containing a group Velement (i.e., a group V element precursor) into the reaction chambercontaining the substrate. This results in mixing of the precursors(i.e., the group III element precursor and the group V elementprecursor) before their exposure to the surface of the substrate.

Deposition of III-V semiconductor materials using a MOCVD processinvolves a balance between growth rate at the surface of the substrateand compound formation in the vapor phase. Specifically, mixing of thegroup III element precursor and the group V element precursor may resultin the formation of particles that consume the precursors that areotherwise used to form the III-V semiconductor material on a suitablegrowth substrate. Consumption of available precursors during the MOCVDprocess creates difficulties in controlling the growth rate, thicknessand composition of the III-V semiconductor material, especially in largereaction chambers. Variation in the thickness and composition of theIII-V semiconductor material formed using the MOCVD processes maynegatively affect throughput and yield of devices having a specificemission wavelength, such as wavelength-specific LEDs. Furthermore,deposition rates of III-V semiconductor materials formed by MOCVDprocesses are generally low, thus decreasing throughput and increasingcost per wafer.

Atomic layer deposition (ALD) is a process used to deposit conformalmaterial with atomic scale thickness control. ALD may be used to depositIII-V semiconductor materials. ALD is a multi-step, self-limitingprocess that includes the use of at least two reagents or precursors.Generally, a first precursor is introduced into a reactor containing asubstrate and adsorbed onto a surface of the substrate. Excess precursormay be removed by pumping and purging the reactor using, for example, apurge gas. A second precursor is then introduced into the reactor andreacted with the adsorbed material to form a conformal layer or film ofa material on the substrate. Under select growth conditions thedeposition reaction may be self-limiting in that the reaction terminatesonce the initially adsorbed material reacts fully with the secondprecursor. Excess precursor is again removed by pumping and purging thereactor. The process may be repeated to form another layer of thematerial, with the number of cycles determining the total thickness ofthe deposited film.

III-V semiconductor materials formed utilizing ALD processes may be of ahigher crystalline quality than those formed by conventional MOCVDprocesses. ALD processes may allow for greater control of precursorincorporation into the deposited crystalline material and consequently agreater control of the composition of the crystalline material formed,e.g., of the III-V semiconductor material formed by such ALD processes.Such stringent control of the composition of the III-V semiconductormaterial may be of consequence in light-emitting devices, for example,to ensure a uniform emission wavelength between light-emitting devicesfabricated on a single growth substrate and between light-emittingdevices from growth substrate to growth substrate.

However, the growth rate of III-V semiconductor materials byconventional ALD processes is relatively low in comparison to that ofMOCVD. Furthermore, high throughput of III-V semiconductor materials byconventional ALD requires increased load sizes that make purging excessprecursor and purge gas out of the reactor difficult. Thus, currentlyavailable ALD reactors are often configured for single wafer processing,leading to low throughput and high cost per wafer of III-V semiconductormaterials by ALD.

Recently, ALD methods and systems have been developed in which eachprecursor is provided continuously in spatially separated regions, andeach precursor is introduced to the substrate as the substrate is movedthrough each precursor in succession. Such processes are often referredto in the art as “spatial ALD” or “S-ALD.”

BRIEF SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form, such concepts being further described in the detaileddescription below of some example embodiments of the invention. Thissummary is not intended to identify key features or essential featuresof the claimed subject matter, nor is it intended to be used to limitthe scope of the claimed subject matter.

In some embodiments, the present invention includes method of depositingmaterial, such as a III-V semiconductor material, on a substrate. Agroup III element precursor and a group V element precursor may beintroduced into alternating gas injectors of a plurality ofsubstantially aligned gas injectors. A substrate may be moved relativeto the plurality of substantially aligned gas injectors such that asurface of the substrate is exposed to the group III element precursorand the group V element precursor forming at least one III-Vsemiconductor material on the surface of the substrate.

In additional embodiments, the present invention includes depositionsystems for forming semiconductor materials. The deposition systems mayinclude a manifold including a plurality of substantially aligned gasinjectors and at least one assembly for moving a substrate along alength of the manifold. At least one of the plurality of substantiallyaligned gas injectors includes an inlet, a thermalizing conduit, aliquid container configured to hold a liquid reagent therein, and anoutlet. A pathway extends from the inlet, through the thermalizingconduit to an interior space within the liquid container, and from theinterior space within the liquid container to the outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be understood more fully by reference to thefollowing detailed description of example embodiments of the presentinvention, which are illustrated in the appended figures in which:

FIG. 1 is a cross-sectional view schematically illustrating an exampleembodiment of a deposition system of the invention that includes amanifold including at least one gas injector as described herein;

FIG. 2 schematically illustrates an example embodiment of a gas injectorof the invention, one or more of which may be used in embodiments ofdeposition systems of the invention, such as the deposition system ofFIG. 1;

FIG. 3 is an enlarged, partially cut-away view of a portion of the gasinjector of FIG. 2;

FIG. 4 schematically illustrates another embodiment of a gas injector ofthe invention that is similar to that of FIG. 2, but further includesactive and passive heating elements;

FIG. 5 schematically illustrates another example embodiment of a gasinjector of the invention, one or more of which may be used inembodiments of deposition systems of the invention, such as thedeposition system of FIG. 1;

FIG. 6 schematically illustrates another embodiment of a gas injector ofthe invention that is similar to that of FIG. 5, but further includesactive and passive heating elements;

FIG. 7 schematically illustrates another embodiment of a gas injector,one or more of which may be used to inject precursor gases ontosubstrates in embodiments of deposition systems of the invention, suchas the deposition system of FIG. 1;

FIGS. 8A through 8D schematically illustrate examples of embodiments ofgas mixtures that may be supplied to the at least one gas injector ofthe manifold; and

FIG. 9 is a top down view schematically illustrating an example ofembodiment of a deposition system and method of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The illustrations presented herein are not meant to be actual views ofany particular component, device, or system, but are merely idealizedrepresentations that are employed to describe embodiments of the presentinvention.

A number of references are cited herein, and the disclosures of whichare incorporated herein, in their entireties, by this reference for allpurposes. Further, none of the cited references, regardless of howcharacterized herein, are admitted as prior art relative to theinvention of the subject matter claimed herein.

As used herein, the term “III-V semiconductor material” means andincludes any semiconductor material that is at least predominantlycomprised of one or more elements from group IIIA of the periodic table(B, Al, Ga, and In) and one or more elements from group VA of theperiodic table (N, P, As and Sb). For example, III-V semiconductormaterials include, but are not limited to, gallium nitride, galliumphosphide, gallium arsenide, indium nitride, indium phosphide, indiumarsenide, aluminum nitride, aluminum phosphide, aluminum arsenide,indium gallium nitride, indium gallium phosphide, indium galliumarsenide, aluminum gallium nitride, aluminum gallium phosphide, aluminumgallium arsenide, indium gallium nitride phosphide, etc.

As used herein, the term “gas” includes gases (fluids that have neitherindependent shape nor volume) and vapors (gases that include diffusedliquid or solid matter suspended therein), and the terms “gas” and“vapor” are used synonymously herein.

As used herein, the term “ALD growth cycle” means and includes exposinga surface of a substrate to a first precursor, chemisorption of thefirst precursor onto the surface of the substrate, exposing the surfaceof the substrate to a second precursor, and a surface reaction to form alayer of material.

Methods and systems that utilize an external source of one or more metalhalides, such as, for example, gallium trichloride (GaCl₃), indiumtrichloride (InCl₃), and/or aluminum trichloride (AlCl₃) as precursorshave recently been developed. Examples of such methods and systems aredisclosed in U.S. Patent Application Publication No. US 2009/0223442 A1,which published Sep. 10, 2009 in the name of Arena et al., the entiredisclosure of which application is incorporated herein in its entiretyby this reference. Further, improved gas injectors have also beenrecently developed for use in such methods and systems. Examples of suchgas injectors are disclosed in, for example, U.S. Provisional PatentApplication Ser. No. 61/157,112, which was filed on Mar. 3, 2009 in thename of Arena et al., and in U.S. patent application Ser. No.12/894,724, which was filed Sep. 30, 2010 in the name of Ronald T.Bertran, Jr. and entitled “Thermalizing Gas Injectors for GeneratingIncreased Precursor Gas, Material Deposition Systems Including SuchInjectors, and Related Methods,” the entire disclosure of each of whichapplication is incorporated herein in its entirety by this reference.

The metal halides are classified as inorganic ALD precursors. The use ofsuch inorganic metal halide precursors for ALD processes may beadvantageous over, for example, organic precursors since they aregenerally smaller, more reactive, thermally stable and usually leavesmall amounts of ligand residues in the deposited crystalline material.Small ligands reduce the risk of steric hindrance and, as a result,reduce growth per cycle. High thermal stability enables depositionwithout thermal decomposition at higher temperatures.

Embodiments of the present invention include, and make use of, new gasinjectors in an atomic layer deposition (ALD) process, as described infurther detail below. An example of an embodiment of a deposition system100 of the invention that includes a plurality of gas injectors 102A,102B, 102C, 102D, such as those described in U.S. Provisional PatentApplication Ser. No. 61/157,112 or U.S. patent application Ser. No.12/894,724 is described below with reference to FIG. 1. Each of the gasinjectors 102A, 102B, 102C, 102D may be configured to convert a sourcegas to one or more precursors for use in the ALD process. The depositionsystem 100 may provide a series of ALD growth cycles, each growth cycleforming a layer of a III-V semiconductor material. The deposition system100 may, thus, be employed in forming a plurality of layers of III-Vsemiconductor material, each having a desired composition and thickness,for use in device structure formation including, for example,light-emitting diodes (LEDs) and the like.

The deposition system 100 may further include a manifold 104 and anassembly 106, such as a track, a conveyor or a support. The manifold 104may include a plurality of gas columns 108 configured to receive atleast one gas through a port 110 therein. The gas columns 108 may bepositioned in longitudinal alignment with one another to form themanifold 104. The gas columns 108 of the manifold 104 may be arranged inany suitable configuration, such as a linear, a folded or a serpentineconfiguration. In some embodiments, the manifold 104 is configured tomove relative to one or more workpiece substrates 112 (e.g., one or moredies or wafers) on which it is desired to deposit or otherwise provideIII-V semiconductor material, as indicated by directional arrow 103. Inother embodiments, the assembly 106 is configured to move the workpiecesubstrate 112 relative to the gas columns 108 of the manifold 104, asindicated by directional arrow 105. For example, the workpiecesubstrates 112 may comprise dies or wafers. The gas columns 108 may,therefore, be positioned at a sufficient distance above the assembly 106for the workpiece substrate 112 to be moved through a space between thegas columns 108 and the assembly 106.

In the following description of the deposition system 100 and, moreparticularly, the manifold 104 of the deposition system 100, the terms“longitudinal” and “transverse” are used to refer to the directionsrelative to the manifold 104 and the assembly 106 and as shown in FIG.1, wherein the longitudinal direction is the horizontal direction fromthe perspective of FIG. 1, and the transverse direction is the verticaldirection from the perspective of FIG. 1. The longitudinal directionsare also referred to as directions extending “along a length of themanifold” or “along a length of the assembly.”

In some embodiments, the deposition system 100 includes a gas flowsystem used to supply one or more gases into the manifold 104 and toremove gases out of the manifold 104.

For example, the deposition system 100 may include gas sources 114A,114B, 114C, 114D that supply the gases to respective gas injectors 102A,102B, 102C, 102D.

For example, one or more of the gas sources 114A, 114B, 114C, 114D maycomprise an external source of a group III element or a group V elementthat may be supplied to the gas injectors 102A, 102B, 102C, 102D. Thegroup III element source may include at least one of a source of gallium(Ga), a source of indium (In) and a source of aluminum (Al). As anon-limiting example, the group III element source may comprise at leastone of gallium trichloride (GaCl₃), indium trichloride (InCl₃) andaluminum trichloride (AlCl₃). The group III element source, comprisingat least one of GaCl₃, InCl₃ or AlCl₃, may be in the faun of a dimersuch as, for example, Ga₂Cl₆, In₂Cl₆ or Al₂Cl₆. The group V elementsource may include a source of nitrogen (N), a source of arsenic (As)and/or a source of phosphorus (P). By way of example and not limitation,the group V element source may comprise one or more of ammonia (NH₃),arsine (AsH₃) or phosphine (PH₃). In some embodiments, source gases maybe supplied from the gas sources 114A, 114B, 114C, 114D to the gasinjectors 102A, 102B, 102C, 102D using one or more carrier gases, suchas hydrogen gas (H₂), helium gas (He), argon (Ar), etc. The source gasmay therefore comprise one or more group III element sources as well asone or more carrier gases.

As the source gas is conveyed from the gas sources 114A, 114B, 114C,114D through conduits 116, the source gas may be heated to a temperaturesufficient to generate a precursor gas from the source gas. For example,the source gas may include GaCl₃ and H₂, which may be heated to atemperature sufficient for the gallium trichloride to dissociate in thepresence of hydrogen into gallium chloride (GaCl) and a chlorinatedspecies, such as hydrogen chloride gas (HCl) and/or chlorine gas (Cl₂).

The gas sources 114A, 114B, 114C, 114D may supply source gas to the gasinjectors 102A, 102B, 102C, 102D. Each of the gas injectors 102A, 102B,102C, 102D may be configured for generating one or more precursors andfor introducing the precursors to the workpiece substrate 112. Forexample, the gas injectors 102A, 102B, 102C, 102D may be configured tosupply precursor gases to the elongated gas columns 108, which may beconfigured to direct the precursor gases toward the major surface of theworkpiece substrate 112 in a direction substantially perpendicular tothe major surface of the workpiece substrate 112. Thus, an area on theassembly 106 underlying each of the gas columns 108 represents aninjection point at which the workpiece substrate 112 is exposed to theprecursor gases.

The gas injectors 102A, 102B, 102C, 102D may each operate independentlyand may be spaced from adjacent gas injectors 102A, 102B, 102C, 102D ata distance sufficient to prevent cross-contamination of gases releasedby adjacent injectors 102A, 102B, 102C, 102D. Each of the gas injectors102A, 102B, 102C, 102D may be configured to provide a sufficient amountof gas to saturate a surface of the workpiece substrate 112 and deposita layer of a material on the surface of the workpiece substrate 112. Themanifold 104 of the deposition system 100 shown in FIG. 1 is depictedwith four gas injectors 102A, 102B, 102C, 102D; however, any number ofgas injectors may be used. For example, the number of gas injectors usedto supply a precursor (e.g., a group III element precursor or a group IVelement precursor) to the workpiece substrate 112 may be selected basedon a desired thickness of the material (e.g., the III-V semiconductormaterial).

In embodiments where the group III element precursor is formed from agas comprising GaCl₃, InCl₃, or AlCl₃, the group III element precursormay be formed from the gas using at least one of the gas injectors 102A,102B, 102C, 102D, as will be described.

The deposition system 100 also includes features for maintainingseparation of the precursor gases during deposition of the III-Vsemiconductor material. For example, the deposition system 100 mayinclude at least one purge gas source 118 for supplying a purge gas tocorresponding gas columns 108 and an exhaust line 120 for drawing excessprecursor gases from the deposition system 100, as indicated bydirectional arrow 121. The purge gas source 118 may comprise a purgegas, such as argon (Ar), nitrogen (N₂), and helium (He). The purge gassource 118 may be used to deliver the purge gas to the workpiecesubstrate 112 via the gas columns 108. For example, the purge gas source118 may supply the purge gas to at least one of the gas columns 108disposed between two of the gas columns 108 used to supply theprecursors to the workpiece substrate 112. The gas columns 108 may alsobe used to remove excess gases (i.e., the precursor gases and the purgegases) from a surface of the workpiece substrate 112. The excess gasesmay be passed through the gas columns 108 and into the exhaust line 120for removal from the deposition system 100. For example, the excessgases may be removed through one of the gas columns 108 disposed betweeneach of the gas columns 108 configured to supply the precursor gases andpurge gas to the workpiece substrate 112.

The assembly 106 is configured to support the workpiece substrate 112and, in some embodiments, to transport the workpiece substrate 112 insequence under each successive gas column 108. Although a singleworkpiece substrate 112 is shown in FIG. 1, the assembly 106 may beconfigured to support any number of workpiece substrates 112 forprocessing. In some embodiments, the assembly 106 may transport theworkpiece substrate 112 along a length of the manifold 104. Theworkpiece substrate 112 and the manifold 104 may be moved relative toone another at a speed that enables each of the precursor gasesgenerated by the corresponding gas injector 102A, 102B, 102C, 102D tosaturate the surface of the workpiece substrate 112. As the surface ofthe workpiece substrate 112 is exposed to each of the precursors, alayer of material may be deposited over the surface of the workpiecesubstrate 112.

As the workpiece substrate 112 is moved relative to the gas columns 108,a plurality of ALD growth cycles for forming a III-V semiconductormaterial over the surface of the workpiece substrate 112 may becompleted.

As previously mentioned, one or more of the gas injectors 102A, 102B,102C, 102D of the deposition system 100 may be or include one of thevarious embodiments of gas injectors described in detail with referenceto FIGS. 2 through 7. In some embodiments, the gas injectors 102A, 102B,102C, 102D may include a thermalizing gas injector as described in U.S.Patent Application Ser. No. 61/157,112, but further including areservoir configured to hold a liquid reagent for reacting with a sourcegas (or a decomposition or reaction product of a source gas). Forexample, the reservoir may be configured to hold a liquid metal or otherelement, such as, for example, liquid gallium, liquid aluminum, orliquid indium In some embodiments, the reservoir may be configured tohold one or more solid materials, such as, for example, iron, silicon,or magnesium.

FIG. 2 is a perspective view of an embodiment of a gas injector 200 ofthe invention. As shown in FIG. 2, the gas injector 200 includes aninlet 202, an outlet 204, a thermalizing conduit 206, and a container210. The container 210 is configured to hold a liquid reagent therein.For example, a liquid metal such as liquid gallium, liquid indium,liquid aluminum, etc., may be disposed within the container 210. Asource gas, comprising for example, GaCl₃ and H₂, may be supplied to theinlet 202. The source gas may flow from the inlet 202 into thethermalizing conduit 206. The thermalizing conduit 206 may be configuredto heat the source gas flowing through the thermalizing conduit 206 fora desirable amount of time (i.e., a residence time), which may be afunction of the cross-sectional area of the flow path within thethermalizing conduit 206, the flow rate of the source gas through thethermalizing conduit 206, and the overall length of the thermalizingconduit 206. The thermalizing conduit 206 may be shaped and configuredto be located proximate to one or more active or passive heatingelements, as discussed in further detail below.

Furthermore, the thermalizing conduit 206 may include one or more curvedsections or turns, such that the length of the physical space occupiedby the thermalizing conduit 206 is significantly less than the actuallength of the flow path through the thermalizing conduit 206. Statedanother way, a length of the thermalizing conduit 206 may be longer thana shortest distance between the inlet 202 and the liquid container 210.In some embodiments, the length of the thermalizing conduit 206 may beat least about twice the shortest distance between the inlet 202 and theliquid container 210, at least about three times the shortest distancebetween the inlet 202 and the liquid container 210, or even at leastabout four times the shortest distance between the inlet 202 and theliquid container 210. For example, the thermalizing conduit 206 may havea serpentine configuration, as shown in FIG. 2 that includes a pluralityof generally parallel straight sections connected together in anend-to-end fashion by curved sections that extend through an angle of180°.

The thermalizing conduit 206 may comprise a tube that is at leastsubstantially comprised of a refractory material such as, for example,quartz.

In some embodiments, the source gas may at least partially decomposewithin the thermalizing conduit 206. For example, in embodiments inwhich the source gas comprises GaCl₃ and H₂, the GaCl₃ may decompose inthe presence of H₂ into gaseous GaCl and a chlorinated gas species, suchas, for example, hydrogen chloride gas (HCl) and/or chlorine gas (Cl₂).

The gases flow from the thermalizing conduit 206 into the container 210.FIG. 3 is an enlarged, partially cut-away view of the container 210. Asshown in FIG. 3, the container 210 includes a bottom wall 212, a topwall 214, and at least one side wall 216. In the embodiment of FIGS. 2and 3, the reservoir has a generally cylindrical shape, such that eachof the bottom wall 212 and the top wall 214 has a circular shape and isat least substantially planar, and such that the side wall 216 is atleast substantially cylindrical (e.g., tubular). The bottom wall 212,the top wall 214, and the at least one side wall 216 together define ahollow body, the interior of which defines a reservoir for holding aliquid reagent, such as liquid gallium.

The interior space within the hollow container 210 may be partiallyfilled with a liquid reagent, such as liquid gallium, liquid indium andliquid aluminum. For example, the container 210 may be filled with theliquid reagent to the level indicated by the dashed line 220 in FIG. 3,such that a void or space 222 is present over the liquid reagent withinthe container 210. Gases flowing out from the thermalizing conduit 206may be injected into the space 222 over the liquid reagent within thecontainer 210. As a non-limiting example, the gases flowing out from thethermalizing conduit 206 may flow through the bottom wall 212 into atube 224. In some embodiments, the tube 224 may comprise an integralportion of the thermalizing conduit 206 that extends into the container210. The tube 224 may extend through the liquid reagent disposed withinthe container 210 to the space 222 over the liquid reagent. The tube 224may comprise a ninety-degree bend, such that an end portion of the tube224 extends horizontally over the liquid reagent. As shown in FIG. 3, anaperture 226 may be provided through the cylindrical side wall of thetube 224 on a side thereof facing the surface of the liquid reagent,such that gases flowing through the tube 224 will exit the tube 224through the aperture 226. The gases exiting the aperture 226 may bedirected out from the aperture 226 in a direction oriented toward thesurface of the liquid reagent to promote reaction between one or morecomponents of the gases and the liquid reagent.

For example, in embodiments in which the source gas comprises GaCl₃ anda carrier gas, such as H₂, and the source gas has decomposed to includegaseous GaCl and a chlorinated gas species within the thermalizingconduit 206, the liquid reagent within the container 210 may compriseliquid gallium, which may react with the chlorinated gas species (e.g.,HCl) generated within the thermalizing conduit 206 to form additionalgaseous GaCl. Alternatively, the liquid reagent within the container 210may comprise liquid indium or liquid aluminum, which may respectivelyreact with the chlorinated gas species (e.g., HCl) to form InCl or AlCl.The gases within the space 222 over the liquid reagent within thecontainer 210 may flow out from the container through an outlet port228. For example, the outlet port 228 may be located in the top wall 214of the container 210 over the horizontally extending portion of the tube224. The outlet port 228 may lead to an outlet conduit 230, an end ofwhich may define the outlet 204 of the gas injector 200 (FIG. 2).

The various components of the container 210 may be at leastsubstantially comprised of a refractory material such as, for example,quartz.

The GaCl may be a desirable precursor gas for forming GaN. Thus, byconverting the excess chlorinated gas that results from thermaldecomposition of GaCl₃ (in systems that employ GaCl₃ as a source gas)into additional GaCl, detrimental effects of excess chlorinated gasspecies to the deposited GaN material may be avoided, since the amountof chlorinated gas species introduced to the workpiece substrate 112(FIG. 1) may be reduced. Such detrimental effects may include, forexample, incorporation of chlorine atoms into the gallium nitridecrystal lattice and cracking or delamination of deposited GaN film. Inaddition, detrimental effects may include, for example, forming excesshydrogen chloride gas (HCl). The hydrogen chloride may act as an etchantto a deposited III-nitride layer within deposition system 100 therebyreducing the growth rate or even preventing deposition of theIII-nitride. Furthermore, by reacting the excess chlorinated specieswith the liquid gallium to form additional GaCl, the efficiency of thedeposition system 100 may be improved.

FIG. 4 illustrates another embodiment of a thermalizing gas injector 300that includes the gas injector 200 of FIG. 2, as well as active andpassive heating components for heating at least the thermalizing conduit206 and the container 210 of the gas injector 200. In other words, atleast one heating element may be disposed proximate at least one of thethermalizing conduit 206 and the container 210 to heat at least one ofthe thermalizing conduit 206 and the container 210 of the gas injector200.

As shown in FIG. 4, the thermalizing gas injector 300 includes acylindrical passive heating element 302 that is disposed within agenerally cylindrical space that is surrounded by the thermalizingconduit 206 of the gas injector 200.

The passive heating element 302 may be at least substantially comprisedof materials with high emissivity values (close to unity) (black bodymaterials) that are also capable of withstanding the high-temperature,corrosive environments that may be encountered within the depositionsystem 100 (FIG. 1). Such materials may include, for example, aluminumnitride (AlN), silicon carbide (SiC), and boron carbide (B₄C), whichhave emissivity values of 0.98, 0.92, and 0.92, respectively.

The passive heating element 302 may be solid or hollow. In someembodiments, the passive heating element 302 may be hollow, and athermocouple may be positioned within the interior space of the passiveheating element 302 for temperature monitoring and control purposes. Inadditional embodiments, a cylindrical thermocouple may be positionedaround the passive heating element 302 and between the passive heatingelement 302 and the surrounding thermalizing conduit 206.

In additional embodiments, hollow cylindrical passive heating elementsmay be disposed over and around one or more straight sections of thethermalizing conduit 206. In such embodiments, a cylindricalthermocouple may be positioned between the hollow cylindrical passiveheating elements and the sections of the thermalizing conduit 206surrounded by the hollow cylindrical passive heating elements.

The thermalizing gas injector 300 also may include an active heatingelement 304. The active heating element 304 may at least partiallysurround each of the thermalizing conduit 206 and the container 210 ofthe gas injector 200. In some embodiments, the active heating element304 may be generally cylindrical and may extend entirely around at leasta portion of each of the thermalizing conduit 206 and the container 210,as shown in FIG. 4. The active heating element 304 may comprise, forexample, at least one of a resistive heating element, an inductiveheating element, and a radiant heating element. An insulating jacket 306may at least substantially surround the gas injector 200, the passiveheating element 302, and the active heating element 304, as shown inFIG. 4, so as to improve the efficiency of the heating process by whichthe active heating element 304 and the passive heating element 302 heatthe thermalizing conduit 206 (or at least the gas or gases containedtherein) and the container 210 (or at least the liquid reagent and gasor gases contained therein).

The active and passive heating elements 304, 302 of the thermalizing gasinjector 300 may be capable of heating the thermalizing conduit 206, thecontainer 210 and the source gas to temperatures between about 500° C.and about 1,000° C.

FIG. 5 illustrates another embodiment of a gas injector 400 of theinvention. The gas injector 400 of FIG. 5 is similar to the gas injector200 of FIG. 2, and includes an inlet 202, and outlet 204, a thermalizingconduit 406, and a container 210. The container 210 may be as describedin relation to FIGS. 2 and 3. The thermalizing conduit 406 issubstantially similar to the thermalizing conduit 206 of FIG. 2, exceptthat the thermalizing conduit 406 extends along a spiral path (i.e., hasa spiral configuration), instead of having a serpentine configuration,as does the thermalizing conduit 206 of FIG. 2.

As shown in FIG. 5, embodiments of the invention may also include anouter housing 450. The outer housing 450 may be configured to encloseand protect at least the thermalizing conduit 406 and the container 210of the gas injector 400. The outer housing 450 may also serve as anadditional gas-conducting conduit that may be used, for example, toconvey purge gases (e.g., purge gases). For example, the outer housing450 may include an inlet port 452 and an outlet port 454, such that agas may flow through the outer housing 450 between the inlet port 452and the outlet port 454. In additional embodiments of the invention, anouter housing 450 may be provided on the gas injector 200 of FIG. 2, thethermalizing gas injector 300 of FIG. 4, or any other gas injectordescribed herein below.

With continued reference to FIG. 5, in operation, a source gas, such asGaCl₃ and H₂, enters the gas injector 400 through the inlet 202 with anincoming flow rate of less than 100 cubic centimeters per minute (sccm),less than 50 sccm, or even less than 10 sccm. The flow rate, however,may be greater than 20 standard liters per minute (SLM), such as, forexample, greater than or equal to 30 SLM. The gaseous precursors, suchas GaCl, exit the gas injector 400 through the outlet 204 attemperatures between about 500° C. and about 1,000° C. A purge gas, suchas nitrogen gas or a mixture of nitrogen gas and hydrogen gas (H₂),enters the outer housing 450 through inlet port 452 with an incomingflow rate of approximately one to five SLM, and maintains anoverpressure in at least the interior of the outer housing 450. Thepurge gas exits the outer housing 450 through the outlet port 454. Thepurge gas may also be heated as it passes through the outer housing 450.

FIG. 6 illustrates another embodiment of a thermalizing gas injector 500that includes a gas injector substantially similar to the gas injector400 of FIG. 5, but without the outer housing 450. Thus, the gas injector500 includes a thermalizing conduit 406 and a container 210, aspreviously described herein. The gas injector 500 further includes aninlet 202 and an outlet 204. The thermalizing gas injector 500 of FIG. 6further includes active and passive heating elements like thosepreviously described in relation to the gas injector 300 of FIG. 4. Inparticular, the gas injector 500 of FIG. 6 includes the previouslydescribed cylindrical passive heating element 302, which is disposedwithin a generally cylindrical space that is surrounded by thespiral-thermalizing conduit 406 of the gas injector 500. Thethermalizing gas injector 500 also may include an active heating element304 and an insulating jacket 306, as previously described in relation toFIG. 4. As previously discussed, the active and passive heating elementsof the thermalizing gas injector 500 may be capable of heating thethermalizing conduit 406, the container 210 and the source gas totemperatures between about 500° C. and about 1,000° C.

FIG. 7 illustrates an example of a gas injector 500 that may be used toinject dopant precursors onto the workpiece substrate 112 of FIG. 1. Thegas injector 500 includes an inlet 202, an outlet 204, and a container210 as previously described in relation to FIGS. 2 and 3. A generallystraight conduit 502 may extend from the inlet 202 to the container 210(in place of the thermalizing conduit 206 of FIGS. 2 and 3). Thecontainer 210 may be configured to hold a liquid metal reagent therein,such as, for example, liquid aluminum and liquid indium. In someembodiments of the invention the container 210 may be configured to holdone or more solid materials, such as, for example, iron, silicon ormagnesium, etc.

The gas injector 500 also may include active and/or passive heatingelements, such as, for example, the active heating element 304 and theinsulating jacket 306 previously described in relation to the gasinjector 300 of FIG. 4. The active and/or passive heating elements maybe used to heat the container 210 (or at least the liquid containedtherein) to temperatures sufficient to maintain the metal within thecontainer 210 in the liquid state.

A source gas, such as gaseous hydrogen chloride, chlorine or gaseousGaCl may be supplied from an external gas source to the inlet 202. Thesource gas may flow from the inlet 202 through the conduit 502 to thecontainer 210, where the source gas may react with the metal reagentwithin the container 210 to form a precursor gas (e.g., InCl, AlCl,FeCl, etc.). The precursor gas may flow out from the container 210through the outlet 204.

The flow rate of the gases through the gas injector 500 relative to theflow rates of the other gas injectors of the deposition system 100 maybe selectively controlled so as to control the concentration of theelements deposited from the dopant precursor in the resulting III-Vsemiconductor material.

As described above, embodiments of thermalizing gas injectors of theinvention may be used to inject gaseous group III element precursors andgroup V element precursors onto the workpiece substrate 112 fordepositing III-V semiconductor materials using an S-ALD process. Forexample, in some embodiments, the thermalizing gas injectors of theinvention may be used to convert GaCl₃ into gaseous GaCl by thermaldecomposition of GaCl₃ in the presence of hydrogen, and by reaction of achlorinated species (e.g., HCl, Cl₂) resulting from such thermaldecomposition of GaCl₃ with liquid gallium, and to inject GaCl onto theworkpiece substrate 112 for the deposition of GaN in an ALD process.

FIGS. 8A through 8D illustrate examples of configurations of conduits116 and gas injectors 102 that may be used to generate the group IIIelement precursors from source gases supplied externally by the gassources 114A, 114B, 114C, 114D (FIG. 1), as indicated by directionalarrows 107. For example, the group III element precursor may begenerated from a gas including one or more group III elements and one ormore carrier gases, or by passing a gas, such as hydrogen chloride (HCl)vapor, over a heated group III element (i.e., liquid gallium, liquidaluminum, liquid indium, etc.) to form a group III precursor gas, suchas GaCl, AlCl or InCl, as described with respect to FIGS. 3 and 7. Byforming the precursor gases as described with respect to FIGS. 8Athrough 8D, a concentration of the precursor gases may be tailored forforming a III-V semiconductor material having a desired composition. Insome embodiments, the conduits 116 may include a plurality of branches126A, 126B, 126C for carrying different precursors to and from theinjectors 102. The branches 126A, 126B, 126C of the conduits 116 mayconverge forming a single gas stream, as indicated by directional arrows109, which may be supplied to the gas columns 108 (FIG. 1).

As shown in FIG. 8A, a precursor mixture including GaCl and at least oneof InCl and AlCl may be formed using the injectors 102. For example,GaCl₃ may be converted to GaCl and a chlorinated gas in a first branch126A of conduit 116 and InCl₃ or AlCl₃ may be respectively converted toInCl or AlCl in a second branch 126B of the conduit 116. In embodimentsin which the precursor mixture includes GaCl and InCl, the precursormixture may be used in forming one or more of InGaN, InGaAs and InGaP onthe workpiece substrate 112 (FIG. 1). In embodiments in which theprecursor mixture includes GaCl and AlCl, the precursor mixture may beused in forming one or more of AlGaN, AlGaAs, AlGaP on the workpiecesubstrate 112 (FIG. 1).

Referring to FIGS. 8B and 8C, two or more group III element precursors,such as two or more of GaCl, AlCl, InCl or FeCl may be formed by passingGaCl₃, from an external source, over a heated group III element source(e.g., an indium source or an aluminum source) using a gas injector 102,such as that described with respect to FIGS. 3 and 7. As a non-limitingexample, GaCl₃ may be passed over a heated indium source to form theInCl and GaCl, over a heated aluminum source to form the AlCl and GaCl,or over a heated iron source to form the FeCl and GaCl. Additional GaClprecursor may be formed by passing at least one of hydrogen chloride andchlorine gas over a gallium source.

In a first branch 126A of the conduit 116, GaCl and at least one ofhydrogen chloride and chlorine gas may be generated from one or more ofGaCl₃ and H₂ using an injector 102 such as that described with respectto FIGS. 3 and 7. In a second branch 126B of the conduit 116, additionalGaCl or an additional group III element precursor may be generated bythe injector 102. In embodiments in which additional GaCl is generated,a chlorinated gas generated from at least one of GaCl₃, hydrogenchloride or hydrogen gas may be reacted with gallium to form additionalGaCl. In embodiments in which the additional group III element precursoris formed, GaCl, hydrogen chloride or chlorine generated from the GaCl₃may be reacted with at least one of indium, aluminum or iron to form theadditional group III element precursor (i.e., InCl, AlCl or FeCl). Thefirst branch 126A and the second branch 126B of the conduit 116converge, resulting in mixing of the gases.

In some embodiments, additional gases that may be used for doping theIII-V semiconductor materials may be added to the conduits 116. As shownin FIG. 8C, GaCl₃ supplied to a first branch 126A of conduit 116 may bemixed with a dopant gas supplied to a second branch 126B of the conduit116. Suitable dopant gases include, but are not limited to,iron-containing gases, dichlorosilane (H₂SiCl₂), silane (SiH_(r)) andsilicon tetrachloride (SiCl₂). Optionally, a third branch 126C ofconduit 116 may be used to generate an additional group III elementprecursor or additional GaCl, as described with respect to FIG. 8B.

In additional embodiments shown in FIG. 8D, a conduit 116 may includebranches 126A, 126B, and 126C and one of GaCl₃, InCl₃ and AlCl₃ may besupplied in at least two of the branches 126A, 126B, 126C to form a gascomprising a mixture of at least two of GaCl₃, InCl₃ and AlCl₃. Thecombination of at least two of GaCl₃, InCl₃ and AlCl₃ may be used toform ternary group III compounds, such as, for example, InGaN or AlGaN,and quaternary group III compounds, such as, for example, AlInGaN.

The deposition system 100 described with respect to FIG. 1 may beemployed in a method of forming the III-V semiconductor material byS-ALD. For example, the method may employ a plurality of ALD growthcycles 122, 124 for forming the III-V semiconductor material, each ofthe ALD growth cycles including exposing the workpiece substrate 112 toat least one group III precursor and at least one group V precursor.Excess precursor and purge gas may be removed by the gas columns 108connected to the exhaust line 120 to prevent mixing of the at least onegroup III precursor and the at least one group V precursor. Each ALDgrowth cycle 122, 124 may, therefore, form a layer of a specific III-Vsemiconductor material. Any number of ALD growth cycles may be performedusing the deposition system 100 to form a desired thickness of thespecific III-V semiconductor material or to form a plurality of layersof different III-V semiconductor materials. The precursors supplied tothe workpiece substrate 112 during each of the growth cycles may betailored to form the desired III-V semiconductor material or the desiredplurality of layers of different III-V semiconductor materials on theworkpiece substrate 112. For example, the method may be used to form aplurality of layers including III-V semiconductor materials havingdifferent compositions useful in device layers, such as those of LEDs.

At least one of the assembly 106 and the manifold 104 is configured toestablish movement of the workpiece substrate 112 relative to themanifold 104. The workpiece substrate 112 may be positioned on theassembly 106 and moved relative to the manifold 104 through a series ofinjection positions along the length of the manifold 104 (i.e.,positions underlying each of the longitudinally aligned gas injectors102A, 102B, 102C, 102D). At each of the injection positions, theworkpiece substrate 112 may be exposed to the at least one group IIIelement precursor or the at least one group V element precursor by theoverlying gas injector 102A, 102B, 102C, 102D such that a layer of agroup III material, a group V material or a group III-V compoundmaterial is deposited on the workpiece substrate 112. The gas injectors102A, 102B, 102C, 102D may be programmed to control the precursor flowrate and composition to form the desired III-V semiconductor material.

The group III element precursor may be formed from a group III elementsource using embodiments of the thermalizing gas injectors of theinvention, which were previously described. In some embodiments, atleast one of GaCl₃, InCl₃ and AlCl₃ and one or more carrier gases, suchas H₂, N₂ and Ar, may be thermalized using the gas injectors 102A, 102B,102C, 102D to form the group III element precursor (i.e., GaCl, InCl andAlCl). In other embodiments, the group III element source including amixture of gases, such as GaCl₃, InCl₃ and AlCl₃, may be used to formternary and quaternary III-V semiconductor materials, such as InGaN,InGaAs, InGaP, AlGaN, AlGaAs and AlGaP. For example, the mixture ofgases may be formed prior to entry into the gas injectors 102A, 102B,102C, 102D, as described with respect to FIGS. 8A through 8D. Suchmixtures may be used to form ternary and quaternary III-V semiconductormaterials on the workpiece substrate 112. For example, a mixture ofGaCl₃ and InCl₃ may be supplied to one or more of the gas injectors102A, 102B, 102C, 102D for forming InGaN, InGaAs or InGaP on theworkpiece substrate 112 or a mixture of GaCl₃ and AlCl₃ may be suppliedto the gas injectors 102A, 102B, 102C, 102D for forming AlGaN, AlGaAs orAlGaP on the workpiece substrate 112. A ratio of the gases in themixture may be adjusted to form the III-V semiconductor material havinga desired composition.

The group V element precursor may be formed by thermalizing a group Velement source or by other techniques known in the art (e.g., plasmageneration techniques). For example, at least one of ammonia (NH₃),arsine (AsH₃) and phosphine (PH₃) may be thermalized to form the group Velement precursor.

In some embodiments of the invention, one or more of the gas injectors102A, 102B, 102C, 102D may be used to generate a group III elementprecursor, such as GaCl, InCl or AlCl, and to expose a major surface ofthe workpiece substrate 112 to the group III element precursor. Inadditional embodiments of the invention, one or more of the gasinjectors 102A, 102B, 102C, 102D may be used to generate different groupIII element precursors that may be used to form group III nitridecompound materials that include two or more different group III elementssuch as, for example, InGaN, AlGaN, InAlGaN, etc. By way of example andnot limitation, first and third gas injectors 102A, 102C may be used tosupply one or more of GaCl (by converting GaCl₃ into gaseous GaCl bythermal decomposition of GaCl₃, and by reaction of chlorinated speciesresulting from such thermal decomposition of GaCl₃ with liquid gallium),InCl (by converting InCl₃ into gaseous InCl by thermal decomposition ofInCl₃, and by reaction of chlorinated species resulting from suchthermal decomposition of InCl₃ with liquid indium) and AlCl (byconverting AlCl₃ into gaseous AlCl by thermal decomposition of AlCl₃,and by reaction of chlorinated species resulting from such thermaldecomposition of InCl₃ with liquid indium), and second and fourth gasinjectors 102B, 102D may be used to supply gaseous ammonia (NH₃),gaseous arsine (AsH₃), or gaseous phosphine (PH₃). Each gas injector102A, 102B, 102C, 102D may introduce a sufficient amount of precursorgas to the workpiece substrate 112 to deposit a layer of material on theworkpiece substrate 112. The deposition system 100 may include anynumber of gas injectors 102A, 102B, 102C, 102D for depositing thedesired thickness of the III-V semiconductor material or the pluralityof layers of different III-V semiconductor materials on the workpiecesubstrate 112. In addition, the workpiece substrate 112 may be passedthrough the deposition system 100 any number of times to obtain adesirable thickness of the III-V semiconductor material or the pluralityof layers of different III-V semiconductor materials.

In yet additional embodiments of the invention, at least one of the gasinjectors 102A, 102B, 102C, 102D may be used to generate a dopantprecursor (e.g., iron chloride (FeCl) or a vapor phase speciescomprising silicon (Si)) that may be used to introduce a dopant (e.g.,iron atoms or ions or silicon atoms or ions) to the III-V semiconductormaterial. During the deposition process, the dopant precursor maydecompose and/or react with another substance in such a manner as toresult in the dopant being incorporated into the III-V semiconductormaterial being deposited. In such embodiments, it may not be necessaryto thermally decompose the dopant precursor in the gas injector used toinject the dopant precursor.

By way of non-limiting example, each of the ALD growth cycles 122, 124may be used to form a layer of the III-V semiconductor material having adesired composition or a plurality of layers of III-V semiconductormaterial, each having a different composition. A first ALD growth cycle122 may be performed to deposit a first layer of III-V semiconductormaterial. As the workpiece substrate 112 moves along the length of themanifold 104 through a first ALD growth cycle 122, the workpiecesubstrate 112 may be positioned under the gas column 108 incommunication with the first injector 102A. The first injector 102A maysupply the group III element precursor to the workpiece substrate 112through the corresponding gas column 108 and the group III element maybe absorbed on the surface of the workpiece substrate 112.

Excess gases or group III element precursor may be removed from theworkpiece substrate 112 by pumping the gases from the surface of theworkpiece substrate 112 through the gas columns 108 connected to theexhaust line 120. A purging act may also be performed between pumpingacts by exposing the surface of the workpiece substrate 112 to the purgegas.

The workpiece substrate 112 may then be moved relative to the manifold104 to a position under the second injector 102B. The workpiecesubstrate 112 may be exposed to the group V element precursor suppliedby the second injector 102B. The second injector 102B may introduce asufficient amount of the group V element precursor to the workpiecesubstrate 112 that the group V element reacts with the group III elementdeposited on the surface of the workpiece substrate 112 by the firstinjector 102A to form the first layer of III-V semiconductor material.Excess gases or group V element precursor may be removed from theworkpiece substrate 112 by pumping and purging, as previously described.The ALD growth cycle 122 may be repeated any number of times to increasea thickness of the first layer of III-V semiconductor material.

Another ALD growth cycle 124 may be performed to deposit a second layerof III-V semiconductor material having a composition different from thatof the first layer of III-V semiconductor material. As the workpiecesubstrate 112 is moved relative to the manifold 104 through the secondALD growth cycle 124, the workpiece substrate 112 may be positionedunder the third injector 102C. The third injector 102C may introduce thegroup III element precursor to the workpiece substrate 112 and the groupIII element may be absorbed on the surface of the workpiece substrate112.

Excess gases or precursor may be removed from the workpiece substrate112 by pumping and purging, as previously described.

After removing the excess gases, the workpiece substrate 112 may bemoved relative to the manifold 104 to a position under the fourthinjector 102D. The fourth injector 102D may introduce the group Velement precursor to the workpiece substrate 112 and the group V elementmay react with the group III element deposited on the surface of theworkpiece substrate 112 to form the second layer of III-V semiconductormaterial. The ALD growth cycle 124 may be repeated any number of timesto increase a thickness of the second layer of III-V semiconductormaterial.

The thickness of the layer of III-V semiconductor material formed in oneof the ALD growth cycles 122, 124 may depend on the precursors used andthe speed of relative movement of the workpiece substrate 112 along thelength of the manifold 104. Any number of ALD growth cycles 122, 124 maybe performed to deposit a desired thickness of the III-V semiconductormaterial or to form layers of the III-V semiconductor materials havingdifferent compositions. The types of precursors introduced to theworkpiece substrate 112 by the gas injectors 102A, 102B, 102C, 102D maybe tailored to form the desired III-V semiconductor material or thedesired plurality of layers of III-V semiconductor materials. Inembodiments where a structure including a plurality of layers of III-Vsemiconductor materials is formed, the desired thickness of a specificIII-V semiconductor material may be formed on the workpiece substrate112 by performing one or more first ALD growth cycles 122 and,thereafter, one or more second ALD growth cycles 124 may be performed toform a desired thickness of another, different III-V semiconductormaterial. The ALD growth cycles 122,124 may be tailored to control thethickness and composition of each layer of III-V semiconductor materialdeposited using the deposition system 100.

Relative movement of the workpiece substrate 112 and the manifold 104enables continuous, sequential exposure of the workpiece substrate 112to different precursors without loading and unloading the workpiecesubstrate 112 from a reaction chamber between ALD growth cycles, as withconventional CVD systems, temperature ramps, cleaning, pump down, etc.The speed of the relative movement of the workpiece substrate 112 withrespect to the manifold 104 may be varied according to a reaction timeof the precursors, providing a high growth rate of the III-Vsemiconductor materials. The thickness and composition of each of theIII-V semiconductor materials deposited may be determined by a number ofinjection positions (i.e., positions under each of the gas columns 108corresponding to the gas injectors 102A, 102B, 102C, 102D) in thedeposition system 100 and the type of precursors introduced to theworkpiece substrate 112 at each of these injection positions. Thus, thedeposition system 100 enables accurate control of the thickness and thecomposition of each of the III-V semiconductor materials. The depositionsystem 100 may be configured to deposit any combination of III-Vsemiconductor material layers, each having a desired thickness andcomposition. The deposition system 100, and related methods, furtherprovide substantially increased throughput of III-V semiconductormaterials in comparison to conventional deposition systems and methods,thus reducing fabrication costs. The deposition system 100 furtherenables fabrication of structures including multiple layers of III-Vsemiconductor materials, such as those used in III-nitride baseddevices, such as Laser Diode, LEDs, high-frequency and power diodes.

The following example serves to explain an embodiment of the presentinvention in more detail. This example is not to be construed as beingexhaustive or exclusive as to the scope of this invention.

FIG. 9 is a top-down view of a deposition system 100 like that shown inFIG. 1 and illustrates use of the deposition system 100 in methods offorming structures including multiple layers of different III-Vsemiconductor materials, in particular, a multi-quantum well LEDstructure. The deposition system 100 may be used to deposit GaN, InN,AlN and III-nitride alloys. The workpiece substrate 112 may comprise atemplate structure, such as n-type GaN material on a sapphire substrate.The GaN material has a thickness in a range of from about 1 μm to about20 μm and may be electrically doped with silicon to produce n-typematerial. The deposition system 100 may be used to form a plurality ofactive layers (not shown) upon the GaN layer of the workpiece substrate112. For example, the active layers may form the basis of a devicestructure, which may comprise an LED. In additional embodiments, theactive layers may be composed and configured to form a laser diode, atransistor, a solar cell, a MEMS, etc.

The deposition system 100 may be maintained at a temperature in a rangeof from about 350° C. to about 750° C. and a pressure in a range of fromabout 1000 mTorr to about 7600 mTorr. As a non-limiting example, gassources may be supplied at a flow rate in a range of from about 1 sccmto about 100 sccm.

In some embodiments, the deposition system 100 may include a pluralityof deposition zones 130A, 130B, 130C, 130D, 130E, 130F, each of which isused to form a structure including a plurality of layers on theworkpiece substrate 112, each of the layers comprising a III-Vsemiconductor material having a specific composition. For example, thestructure may be an LED device layer structure. In embodiments in whicha structure including alternating layers of InGaN and GaN underlying alayer of doped p-type AlGaN and a layer of doped p-type GaN is formed,the deposition system 100 may include first and third deposition zones130A, 130C for depositing an InGaN material, second and fourthdeposition zones 130B, 130D for depositing a GaN material, a fifthdeposition zone 130E for depositing a doped p-type AlGaN material and asixth deposition zone 130F for depositing a doped p-type GaN material.As the workpiece substrate 112 is moved through the zones 130A, 130B,130C, 130D, 130E, 130F of the deposition system 100, alternatingexposures of an appropriate group III precursor and a nitrogen precursormay be introduced to the workpiece substrate 112 to form the desiredIII-V semiconductor material.

In some embodiments, a thickness of 1 nm of the desired III-Vsemiconductor material may be deposited every one (1) meter of themanifold 104. In embodiments in which the assembly 106 comprises a trackor conveyor used to move the workpiece substrate 112 along a length ofthe manifold 104, the track may have a length of about 100 meters tomove the workpiece substrate 112 under a sufficient number of gasinjectors 102A, 102B, 102C, 102D to form a III-V semiconductor material,such as an LED device layer structure, having a thickness of 100 nm. Thedeposition system 100 may be arranged in a variety of configurationsdepending on available space. In embodiments where the deposition systemhas a processing rate of about 1000 wafers per hour, the track may beabout 100 square meters (m²) and assuming a deliver rate of device layerstructures of 1000 wafer per hour. This corresponds to an area pereffective cycle time per wafer of about 0.1 m² per wafer per hour, whichis a substantial improvement over processing rates for conventional CVDreactors.

Additional non-limiting example embodiments of the invention aredescribed below.

Embodiment 1

A method of depositing a semiconductor material, the method comprising:flowing a group III element precursor through a first gas column of aplurality of substantially aligned gas columns; flowing a group Velement precursor through a second gas column of the plurality ofsubstantially aligned gas columns; establishing movement of a substraterelative to the plurality of substantially aligned gas columns; andsequentially exposing a surface of the substrate to the group IIIelement precursor and the group V element precursor to form a III-Vsemiconductor material.

Embodiment 2

The method of embodiment 1, further comprising decomposing a gascomprising at least one group III element to generate the group IIIelement precursor.

Embodiment 3

The method of Embodiment 2, wherein decomposing a gas comprising atleast one group III element to generate the group III element precursorcomprises decomposing at least one of GaCl₃, InCl₃, and AlCl₃ to form atleast one of GaCl, InCl, and AlCl and chlorine.

Embodiment 4

The method of Embodiment 3, wherein decomposing at least one of GaCl₃,InCl₃, and AlCl₃ to form at least one of GaCl, InCl, and AlCl andchlorine comprises decomposing GaCl₃ to form GaCl and chlorine.

Embodiment 5

The method of Embodiment 2 or Embodiment 3, further comprising reactingthe chlorine with liquid gallium to form additional GaCl.

Embodiment 6

The method of any one of Embodiments 1 through 5, further comprisingincreasing a thickness of the III-V semiconductor material by repeatedlyexposing the surface of the substrate to the group III element precursorand the group V element precursor.

Embodiment 7

The method of any one of Embodiments 1 through 6, further comprising:flowing a purge gas through a third gas column disposed between thefirst gas column and the second gas column; and exposing the substrateto the purge gas to remove excess group III element precursor and excessgroup V element precursor from the surface of the substrate.

Embodiment 8

The method of any one of Embodiments 1 through 7, wherein sequentiallyexposing a surface of the substrate to the group III element precursorand the group V element precursor comprises: exposing the surface of thesubstrate to at least one of GaCl, InCl, and AlCl to absorb at least oneof gallium, indium, and aluminum to the surface of the substrate; andexposing the at least one of gallium, indium, and aluminum absorbed onthe surface of the substrate to at least one of nitrogen, arsenic, andphosphorous.

Embodiment 9

The method of any one of Embodiments 1 through 8, wherein sequentiallyexposing a surface of the substrate to the group III element precursorand the group V element precursor to form a III-V semiconductor materialcomprises forming at least one of gallium nitride, indium nitride,aluminum nitride, indium gallium nitride, indium gallium arsenide,indium gallium phosphide, aluminum gallium nitride, aluminum galliumarsenide, and aluminum gallium phosphide.

Embodiment 10

The method of any one of Embodiments 1 through 9, wherein sequentiallyexposing a surface of the substrate to the group III element precursorand the group V element precursor to a III-V semiconductor materialcomprises forming the III-V semiconductor material having a thickness ofabout 100 nm.

Embodiment 11

The method of any one of Embodiments 1 through 10, further comprisingsequentially exposing a surface of the substrate to another group IIIelement precursor and another group V element precursor to form anotherIII-V semiconductor material over the III-V semiconductor material, theanother III-V semiconductor material having a different composition thanthe III-V semiconductor material.

Embodiment 12

A method of depositing a semiconductor material, comprising: thermallydecomposing at least one source gas within a thermalizing gas injectorto form a group III element precursor; directing the group III elementprecursor toward a surface of a substrate through at least one gascolumn to absorb the at least one group III element on a surface of thesubstrate; directing a group V element precursor toward the surface ofthe substrate through at least another gas column substantially alignedwith the at least one gas column to form a III-V semiconductor material.

Embodiment 13

The method of Embodiment 12, further comprising establishing movement ofthe substrate relative to the at least one gas column and the at leastanother gas column.

Embodiment 14

The method of Embodiment 13, wherein establishing movement of thesubstrate relative to the at least one gas column and the at leastanother gas column comprises establishing movement of the substraterelative to the at least one gas column and the at least another gascolumn of a plurality of gas columns.

Embodiment 15

The method of any one of Embodiments 12 through 14, wherein thermallydecomposing at least one source gas within a thermalizing injector toform a group III element precursor comprises thermally decomposing leastone of GaCl₃, InCl₃, and AlCl₃ within the thermalizing gas injector toform at least one of GaCl, InCl, and AlCl and chlorine gas.

Embodiment 16

The method of Embodiment 15, further comprising reacting the chlorinegas with at least one of liquid gallium, liquid indium, and liquidaluminum within the thermalizing gas injector to form at least one ofadditional GaCl, InCl, and AlCl.

Embodiment 17

The method of Embodiment 15 or Embodiment 16, further comprisingreacting the GaCl with at least one of liquid indium, liquid aluminumand liquid iron within the thermalizing gas injector to form at leastone of InGaCl_(x), AlGaCl_(x), and FeGaCl_(x).

Embodiment 18

The method of any one of Embodiments 12 through 17, wherein directingthe group III element precursor toward a surface of a substrate throughat least one gas column to absorb the at least one group III element ona surface of the substrate comprises directing at least one of GaCl,InCl, and AlCl toward a surface of a substrate through the at least onegas column to absorb at least one of gallium, indium, and aluminum onthe surface of the substrate.

Embodiment 19

The method of Embodiment 18, wherein directing at least one of GaCl,InCl, and AlCl toward a surface of a substrate comprises exposing thesubstrate to GaCl.

Embodiment 20

The method of any one of Embodiments 12 through 19, wherein directing agroup V element precursor toward the surface of the substrate through atleast another gas column comprises directing at least one of nitrogen,arsenic, and phosphorous toward the surface of the substrate through theat least another gas column.

Embodiment 21

The method of any one of Embodiments 12 through 20, further comprisingthermalizing at least one of ammonia, arsine, and phosphine to generatethe group V element precursor.

Embodiment 22

The method of any one of Embodiments 12 through 21, further comprisingexposing the surface of the substrate to at least one purge gas toremove at least one of the group III element precursor and the group Velement precursor from the surface of the substrate.

Embodiment 23

A deposition system, comprising: a manifold comprising a plurality ofsubstantially aligned gas columns configured to direct one or moregases, at least one of the substantially aligned gas columns configuredto receive a group III precursor gas from a thermalizing gas injectorcomprising: an inlet; a thermalizing conduit; a liquid containerconfigured to hold a liquid reagent therein; an outlet; and a pathwayextending from the inlet, through the thermalizing conduit to aninterior space within the liquid container, and from the interior spacewithin the liquid container to the outlet; and at least one assembly formoving a substrate relative to the manifold.

Embodiment 24

The deposition system of Embodiment 23, wherein the thermalizing conduithas a length greater than a shortest distance between the inlet and theliquid container.

Embodiment 25

The deposition system of Embodiment 23 or Embodiment 24, furthercomprising at least one liquid group III element within the liquidcontainer.

Embodiment 26

The deposition system of Embodiment 25, wherein the at least one liquidgroup III element comprises at least one of liquid gallium, liquidindium, and liquid aluminum.

Embodiment 27

The deposition system of any one of Embodiments 23 through 26, whereinat least one of the thermalizing conduit and the liquid container is atleast substantially comprised of quartz.

Embodiment 28

The deposition system of any one of Embodiments 23 through 27, furthercomprising at least one heating element disposed proximate at least oneof the thermalizing conduit and the liquid container.

Embodiment 29

The deposition system of any one of Embodiments 23 through 27, whereinthe at least one heating element comprises a passive heating element atleast substantially comprised of at least one of aluminum nitride,silicon carbide, and boron carbide.

Embodiment 30

The deposition system of any one of Embodiments 23 through 27, furthercomprising: at least one gas source; and at least one gas inflow conduitconfigured to carry a source gas from the gas source to the inlet of thethermalizing gas injector.

Embodiment 31

The deposition system of Embodiment 30, wherein the at least one gassource comprises a source of at least one of GaCl₃, InCl₃, and AlCl₃.

Embodiment 32

The deposition system of any one of Embodiments 23 through 31, furthercomprising at least one purge gas nozzle disposed between each of thegas columns of the plurality.

Embodiment 33

The deposition system of any one of Embodiments 23 through 32, whereinanother gas column adjacent the at least one gas column is configured toreceive at least one purge gas.

Embodiment 34

The deposition system of any one of Embodiments 23 through 33, whereinthe at least one assembly for moving a substrate relative to themanifold comprises a track system configured to transport the substratethrough a series of injection positions along the length of themanifold, each injection position underlying one of the plurality of gascolumns.

The embodiments of the invention described above do not limit the scopeof the invention, since these embodiments are merely examples ofembodiments of the invention, which is defined by the scope of theappended claims and their legal equivalents. Any equivalent embodimentsare intended to be within the scope of this invention. Indeed, variousmodifications of the invention, in addition to those shown and describedherein, such as alternate useful combinations of the elements described,will become apparent to those skilled in the art from the description.Such modifications are also intended to fall within the scope of theappended claims.

What is claimed is:
 1. A method of depositing a semiconductor material,comprising: sequentially exposing a surface of a substrate to a groupIII element precursor and a group V element precursor in at least oneatomic layer deposition (ALD) growth cycle and forming a firstIII-nitride semiconductor material over the surface of the substrate;and exposing a surface of the III-nitride semiconductor material to oneor more metal halide precursors and a group V element precursor andforming a second group III-nitride semiconductor material over the firstIII-nitride semiconductor material.
 2. The method of claim 1, whereinforming the first III-nitride semiconductor material over the surface ofthe substrate comprises forming aluminum nitride over the surface of thesubstrate.
 3. The method of claim 2, wherein forming aluminum nitrideover the surface of the substrate comprises forming a layer of aluminumnitride directly on the surface of the substrate.
 4. The method of claim3, further comprising selecting the substrate to comprise a sapphiresubstrate.
 5. The method of claim 4, wherein forming the second groupIII-nitride semiconductor material over the first III-nitridesemiconductor material comprises forming at least one of GaN, InGaN,AlGaN, and InAlGaN over the first III-nitride semiconductor material. 6.The method of claim 5, wherein forming the second group III-nitridesemiconductor material over the first III-nitride semiconductor materialcomprises forming a layer of GaN directly on the layer of aluminumnitride.
 7. The method of claim 6, wherein forming the layer of GaNfurther comprises thermally decomposing a source gas comprising GaCl₃ toform a metal halide precursor comprising GaCl.
 8. The method of claim 5,wherein forming at least one of GaN, InGaN, AlGaN, and InAlGaN furthercomprises thermally decomposing one or more source gases selected fromthe group consisting of GaCl₃, InCl₃, and AlCl₃ and forming one or moremetal halide precursors selected from the group consisting of GaCl,InCl, and AlCl.
 9. The method of claim 4, further comprising forming theone or more metal halide precursors by thermally decomposing one or moresource gases, the one or more source gases selected from the groupconsisting of GaCl₃, InCl₃, and AlCl₃.
 10. The method of claim 1,wherein forming the second group III-nitride semiconductor material overthe first III-nitride semiconductor material comprises forming a galliumnitride semiconductor material.
 11. The method of claim 1, whereinproviding the one or more metal halide precursors comprises forming atleast a portion of the one or more metal halide precursors by reacting achlorinated species with liquid gallium.
 12. The method of claim 11,wherein the one or more metal halide precursors comprises GaCl.
 13. Themethod of claim 11, wherein the chlorinated species comprises one ormore of hydrogen chloride and chlorine.
 14. The method of claim 1,further comprising forming the one or more metal halide precursors bydecomposing at least one of GaCl₃, InCl₃, and AlCl₃ and forming at leastone of GaCl, InCl, and AlCl.
 15. The method of claim 1, furthercomprising exposing the substrate to a purge gas to remove at least oneof excess group III element precursor and excess group V elementprecursor from the surface of the substrate.
 16. The method of claim 1,further comprising doping the second group III-nitride semiconductormaterial by mixing a dopant gas with the one or more metal halideprecursors.
 17. The method of claim 1, further comprising forming one ormore active layers on or over the second group III-nitride semiconductormaterial.
 18. The method of claim 1, further comprising faulting one ormore device structures on or over the second group III-nitridesemiconductor material.
 19. The method of claim 18, wherein the one ormore device structures comprises one or more light-emitting diodes.